Rapid z800 vs. Rapid Z 1000

Everything I read says the 1000 is for the 308. However, when I run the numbers on the distance calculator, the 800 works out much nicer. The numbers match up to the lines on the scope in 100 yard increments.

If you run the numbers on the 1000 the bullet does not even seem to make it the whole distance. So, why would I buy the 1000 instead of the 800?